I have drums on back.
I just found a page that goes through all the parts and proper name and function of each. a distribution block is not a metering block and a proportioning valve is still different than the others. I have a stock distribution block that works on disk and drum set ups. the proportioning valve (on frame rail under driver seat) is different for a disk drum combo than straight drums. but when you add disk to the front you have to add a metering block (the round looking one next to master)to the front brakes system so that it can build pressure before they engage. can someone verify this before I spend the $90 on one.. thanks